KR20000032705A - Structure of hard disc drive cover - Google Patents

Abstract

PURPOSE: A structure of a hard disc drive cover is provided to minimize an internal noise and a vibration of a hard disc drive by forming air spaces between a cover and a cover damper. CONSTITUTION: Air spaces(102,104,106,108) are formed on a cover(100). Airspaces(102,104,106) are formed at three portions of an edge of the cover surface centering around a rotating center axis of a motor. The air space(108) is formed at a side of a voice coil motor(VCM) with a rectangle shape. A cover damper is adhered to the cover(100). Air spaces(102,104,106,108) are formed between the cover(100) and the cover damper.

Description

Hard disk drive cover structure

The present invention relates to a storage device, and more particularly, to a cover structure of a hard disk drive (hereinafter referred to as "HDD") for minimizing internal noise and vibration.

HDD, which is widely used as an auxiliary memory device of computer system, is divided into two parts. First of all, most circuit components are a set of circuits mounted on a printed circuit board (PCB) and are commonly referred to as a printed circuit board assembly (PCBA). Secondly, most of the mechanical parts including some heads, disks, voice coil motors (VCM), actuators, etc., and some circuit parts are embedded, which is commonly referred to as HDA (Head Disk Assembly).

These HDDs are structurally noise sources inside. In other words, the noise generated by the HDD is mainly generated in the spindle motor, the disk, the head, the VCM and the arm, etc. of the HDD. Since the cover and the base surround the noise source, the cover and the base must be designed in consideration of noise and vibration problems. In particular, in the case of the cover, since the thickness is generally thinner than that of the base, the noise is not only directly transmitted to the outside, but also vibration is transmitted by the base, which may create a new noise source.

Thus, as an example of a typical HDD cover these days, a cover damper is attached on the cover to reduce internal noise and vibration. The cover damper is mainly made of a stainless material having a rigidity of about 10 times that of aluminum, which is a cover material.

In recent years, the development of HDD has been modified due to cost reduction and process reasons, and internal components such as spindle motor and VCM are being modified, and in particular, the processing method of the cover covering the upper surface of the hard disk is changing. In one example, the processing method of the cover is changed, and the processing method is changed from casting to sheet metal forming. The modification of the spindle motor, VCM, etc. as in the above example can improve the system performance and can also improve the performance in terms of noise and vibration. However, when the cover is changed from casting to sheet forming, the cover thickness is reduced compared to the existing model, and as a result, the cover is weak in terms of noise and vibration.

Accordingly, even if the thickness of the cover is thinner than the conventional HDD cover is required to improve sound insulation in terms of noise and vibration.

Accordingly, an object of the present invention is to provide a hard disk drive cover structure having a structure for improving the noise and vibration generated in the hard disk drive.

Another object of the present invention is to provide a hard disk drive cover structure having an optimal cover shape by analyzing vibration and noise characteristics.

According to the above object, the present invention is characterized in that in the cover structure of a hard disk drive, an air layer is formed between a cover and a cover damper attached on the cover.

1 is a structural diagram of a hard disk drive to facilitate understanding of an embodiment of the present invention.

2 shows a simplified system in the case where sound is transmitted through a thin plate;

3 shows a simplified system when sound is passed through a hollow plate.

Figure 4 is a view showing the transmission loss characteristics of a single plate.

5 is a view showing a simplified cross-sectional shape of a conventional HDD cover.

Figure 6 is a graph showing the results of calculating the transmission loss of the two covers shown in Figure 5 and Table 2.

7 is a view showing a cross-sectional shape of the HDD cover to which the hollow plate is applied.

8 is a diagram comparing the transmission loss of a single plate and a laminated structure and a hollow plate structure.

9 is a diagram illustrating a cover of an HDD according to a preferred embodiment of the present invention, showing a state in which the cover damper is removed.

FIG. 10 is a diagram illustrating a cover of an HDD according to an exemplary embodiment of the present invention, showing a state in which a cover damper is attached.

FIG. 11 is a sectional view taken along the line BB ′ in the cover of FIG. 10; FIG.

12 is a view showing the physical properties and thickness of the cover 100 and cover damper 110 and the air gap of the air layer 102, 104, 106, 108 shown in Table 6 and Table 7.

FIG. 13 is a view comparing the number of modes in the cover vertical direction (Z-axis) of seven cover models. FIG.

FIG. 14 is a view showing a comparison of vibration displacement in an idling state with respect to a model before modification, a modified model (F model), and a model (G model) in which the cover damper 110 is added to the modified model. FIG.

15 shows three types of cover application models, namely, a cover application model before modification (a), a modified cover application model (b), and a modified cover and cover damper application model (c) in an idling state to achieve a 1/3 sound pressure. Figure showing the results measured in octave band (octave band).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are denoted by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is an HDD structure diagram to help understand the embodiment of the present invention. Referring to FIG. 1, the HDD includes a base 10, a cover 60 fastened to the base 10, and a gasket 70 installed between the base 10 and the cover 60 to perform a sealing function. It includes. The HDD further includes a magnetic head 42 for recording or reading data to disks 20 that rotate at high speed by a spindle motor 30 installed in the base 10 and a track of the disks 20. Actuator 40 with a head) is provided. The actuator 40 is rotatably installed about a pivot shaft 43, and the bobbin installed at one end is moved to the other side as the bobbin installed at one end moves by the operation of the voice coil motor 50 (VCM). The magnetic head 42 installed in the module records or reads data in the track on the desired disk while moving in the radial direction on the disks 20. At this time, the magnetic head 42 installed at the distal end of the head gimbal 44, which is extended from the actuator arm, is lifted by the airflow of the disk surface as the disks 20 rotate at a high speed, so as to maintain a small gap with the disk surface. do. The FPC 52 is provided to supply current and signal to the VCM coil and magnetic head 42 located at the rear end of the actuator 40. The FPC 52 is connected to a printed circuit board having various electronic circuits for controlling the HDD. have.

The example HDD cover 60 shown in FIG. 1 shows that it is fastened to the base 10 by eight screws. Among them, two screwed parts correspond to the central axis of rotation of the spindle motor 30 and the pivot axis 43 of the actuator 40. In the drawings and the following description, it should be understood that the rotational axis of the spindle motor 30 is represented by "A1" and the pivot axis 43 of the actuator 40 is represented by "A2" to help understand the position of the HDD cover 60. .

In the embodiment of the present invention, the vibration and noise characteristics of the HDD are predicted in advance through computer simulation and analytical methods, and the structure of the HDD cover is improved to realize vibration and noise reduction above a reference level level (HDD noise standard). HDD cover structure according to an embodiment of the present invention has a hollow plate structure.

In order to theoretically analyze the vibration and noise characteristics of HDD, the sound loss loss of panel structure is analyzed theoretically. The vibration and noise prediction of a structure in which a noise source mainly exists inside the HDD and the cover and other elements are wrapped around it can be mainly analyzed through finite element analysis and boundary element analysis. However, finite element analysis requires a lot of time and resources depending on the object and scope of analysis. In the embodiment of the present invention, in order to shorten the analysis time, a basic prediction is made through an analytical method, and more accurate results are obtained through finite element analysis.

Since the HDD cover has a relatively thin panel structure, noise generated inside the HDD is radiated through the panel. Therefore, it is necessary to analyze the noise passing through the panel structure by the theoretical method.

Accordingly, (1) sound insulation analysis of thin plates, (2) sound insulation analysis of laminates, (3) sound insulation analysis of hollow plates, and (4) coincidence phenomena and mass law of panels will be explained.

(1) Sound insulation analysis of thin plate

In general, if the sound insulation loss of a panel is to be calculated in a system where sound is radiated through a thin plate, it must be interpreted considering the boundary condition and shape of the panel. However, since it is very difficult to interpret all of them in consideration of the high frequency, it is often interpreted that the panel is assumed to be infinite plate for the convenience of analysis. This is because the sound insulation loss of the panel is largely influenced by the panel boundary condition and shape at low frequency, but mainly by the thickness and physical properties of the panel at high frequency.

When sound radiates through a thin plate, the system can be simplified and represented as shown in FIG. 2. The transmission loss R (Φ) of the sound of this system is expressed by Equation 1 below.

here, ω : Rotation frequency

m: panel density

Φ: incident angle of sound

ρ ₀ : Density of air

c : Speed of sound propagation in air

Equation 1 is a formula representing the transmission loss of sound for any incident. Incident occurs for all angles, but the incident angle that can actually be transmitted is about 0 to 78 degrees. The effective transmission loss based on the experimental results, the effective transmission loss R 'is expressed by Equation 2 below.

Equation 2 is called a field incidence mass law.

(2) Sound insulation analysis of laminate

The case of a laminate is similar to that of a single plate. If only the Leaf should seek from the sum of the areal density of each plate m _i, as shown in an area density m _n Equation (3).

Therefore, the transfer loss R _n of the stack is shown in Equation 4 below.

(3) Sound insulation analysis of hollow plate

In the case of hollow plates, more complex equations should be used, unlike single and laminated plates. The air gaps between the panels shown in Figure 3 must be taken into account as they have a great impact on the transmission losses of this system. In the case of vertical incidence, the ratio of the incident wave p _i and the transmitted wave p _t is expressed by Equation 5 below.

Where Z _1,2 : impedance of each panel

k: wave number of the air layer

d: distance between panels

Therefore, the acoustic transmission loss R _a of this system is as shown in Equation 6 below.

(4) Coincidence phenomenon and mass law of panel

4 is a view showing the transmission loss characteristics of a single plate. The transmission loss can be largely divided into four areas as shown in FIG. 4.

Stiffness control region: A low frequency region controlled by the panel stiffness.

Resonance Zone: A zone determined by the panel's physical properties, geometry, and boundary conditions.

Mass Control Zone: Dominated by panel density.

Coincidence domain: controlled by panel properties and thickness.

Among the above four regions, the mass control region is a region in which the acoustic transmission loss can be obtained using the above Equations 1 to 6. The coincidence region is the panel's critical frequency ( f _cr It is the area where the transmission loss of the system is extremely small. The critical frequency ( f _cr Mass law does not apply in the vicinity of

Table 1 shows the critical frequencies of several materials ( f _cr ) Is the product of panel thickness h (20 ° C air).

Material hf _cr Steel 12.4 Aluminum 12.0 Brass 17.8 Copper 16.3 Glass 12.7 Perspex 27.7 Chipboard 23 Plywood 20 Asbestos cement 17 dense 19 porous 33 light 34

Assuming that the HDD cover is a panel structure, the transmission loss can be calculated using the above equations. In other words, when the transmission loss calculation program is executed by modeling the sound insulation loss of the panel structure, the transmission loss in the plate, the laminate, and the laminate with the air layer can be analyzed.

Figure 5 is a simplified view showing the cross-sectional shape of the HDD cover that is generally applied to the upper surface of the disk.

The model "A" shown in FIG. 5A has a single plate structure, and the model "B" shown in FIG. 5B has a laminated structure in which two different panels overlap. The overall thickness of the two models is the same.

property 'A' model 'B' model Plate① Plate② density (㎏ / ㎥) 2646 2646 7860 elastic modulus (Gpa) 70 70 200 poisson ratio 0.33 0.33 0.3 thickness (mm) 2.6 1.8 0.8

Table 2 shows physical properties and thicknesses of panels used for sound insulation analysis. Comparing the properties and thickness of the two models, the overall thickness is the same as the two models, and the properties of the 'A' model and the plate ① of the 'B' model are made of the same material. However, plate ② of 'B' model is made of material with higher density and rigidity than plate ①.

Figure 6 is a graph showing the results of calculating the transmission loss of the two covers shown in Figure 5 and Table 2. Although the overall thickness is almost the same, the transmission loss shows a difference of about 10dB. This is a phenomenon in the case of single and laminated plates because the transmission loss is determined almost by mass law. In other words, the magnitude of the transfer loss is affected by the size of the surface density rather than the thickness. Therefore, in order to increase the sound insulation loss of the HDD cover, it is preferable to use a material having a high surface density as the cover damper (cover damper) rather than increasing the thickness.

7 is a view showing a cross-sectional shape of the HDD cover to which the hollow plate is applied. In the embodiment of the present invention, the air gap thickness is set in a practically applicable range in consideration of the gap with the disk.

Table 3 is the physical properties and thickness of the panel to be used for the HDD cover according to an embodiment of the present invention. Table 4 shows the physical properties of air.

property Plate① Plate② density (㎏ / ㎥) 2646 7860 elastic modulus (Gpa) 70 200 poisson ratio 0.33 0.3 thickness (mm) 2.6 0.8

air gap (mm) density (㎏ / ㎥) soundvelocity (m / s) 2 1.21 340

In the physical properties shown in Table 3, the plate ② (cover damper) was selected from the material having a higher density than the plate ① similarly to the laminates mentioned in FIGS. 5 and 2. Table 4 shows the physical properties of the air between and around the panel. For convenience of analysis, it is assumed that the air layer and the air outside the panel are the same.

8 is a result of comparing the transmission loss between the single plate and the laminated structure and the hollow plate structure. The overall thickness is the same as 2.56mm for single plate and laminate, and the hollow plate structure varies according to air layer, but the actual panel thickness is 1.6mm smaller than single plate and laminate. Referring to the results shown in FIG. 8, the hollow plate has a smaller overall thickness of the panel than the laminate, but the transfer loss is greatly increased. In particular, in the case of a single plate and a laminate, the transmission loss difference is almost constant at higher frequencies, while in the case of the hollow plate, the structure of the single plate and the laminate is significantly increased. This is because the transfer loss is determined by the mass law in the case of single plate and laminate, but the transfer loss increases with increasing frequency due to the influence of air layer. That is, in the case of the hollow plate, not only the surface density of the panel but also the air layer greatly affects the transmission loss.

In FIG. 8, the transmission loss result of the hollow plate structure shows a frequency range in which the transmission loss is significantly reduced, unlike the single plate and the laminated plate. The frequency is a frequency determined by the material properties of the panel and the thickness of the air layer. This frequency is called the mass-air-mass resonance frequency. In addition, it can be seen that the frequency of this region moves according to the thickness of the air layer. In particular, it can be seen that the frequency decreases significantly as the thickness of the air layer increases. This phenomenon has to be considered carefully when applying hollow plate because it forms a frequency band which is quite weak in terms of transmission loss.

According to the results as described above, it can be seen that the sound insulation performance is improved when the structure of the HDD cover is a hollow plate than a single plate or a laminate. Accordingly, in the embodiment of the present invention, the vibration characteristics of the HDD cover were analyzed using the finite element method.

In the exemplary embodiment of the present invention, the shape of the cover 60 shown in FIG. 1 is defined as a finite element model, and the finite element model is subjected to mode analysis using commercial structural analysis software, for example, MSC / NASTRAN VER.70. The finite element model used is a model with 2106 nodes and 2035 shell elements. In order to verify the results of finite element analysis, the results were compared with the experimental results under free boundary conditions.

Also, in the embodiment of the present invention, eight models A, B, C, D, E, and G, F under the following conditions are set as the fin shape element model, and the natural frequency of the HDD cover is analyzed.

A: Free boundary (without screws)

B: Add boundary condition to screwed part

C: Maximum air layer (B + air layer)

D: Add beads between the disk and the space near the FPC (C + Bead)

E: Add “+” type beads on top of the disc (D + (+) type beads)

F: Add "x" type beads to the top of the disc (C + (x) type beads)

G: Modified model (x-type)

H: Attach the cover damper to the modified model (G + damper)

The natural frequency (unit Hz) analysis results of the eight HDD cover models are shown in Table 5 below.

mode 0 A B C D E G H One 228.06 1299.34 1515.49 1499.71 1500.34 1515.96 1363.20 896.28 2 592.88 1421.04 1606.28 1622.05 1607.16 1604.33 1390.17 954.13 3 1050.98 1512.26 1641.35 1760.91 1775.15 1766.82 1469.16 1110.47 4 1103.67 1593.94 1967.46 1969.05 20206.34 1999.57 1565.27 1144.27 5 1237.67 1935.42 2208.08 2247.87 2247.38 2261.21 1937.12 1493.96 6 1569.85 2276.60 2453.86 2445.65 2472.70 2469.13 2210.15 1853.46 7 1608.57 2308.69 2600.89 2645.69 26616.11 2662.79 2291.17 1920.47 8 1801.70 2525.43 2742.22 2728.09 2794.38 2768.24 2460.01 2035.50 9 2005.32 2734.36 2962.71 3020.10 3025.15 3060.43 2667.54 2186.81 10 2122.50 2760.10 3296.58 3087.63 3164.25 3127.44 2676.92 2300.75 11 2521.36 2849.83 3392.99 3435.43 3326.13 3340.37 2881.62 2573.63 12 2593.28 3025.51 3433.38 3580.32 3536.07 3500.53 2929.73 2616.56 13 2802.24 3374.94 3680.52 3673.49 3697.94 3758.22 3105.07 2822.03 14 3002.73 3474.19 3868.26 3890.99 3735.81 3855.10 3370.14 2927.20 15 3143.64 3657.18 3959.33 4049.22 4013.95 3924.34 3561.43 3153.26 16 3329.17 3681.60 4251.52 4381.07 4153.33 4442.26 3585.60 3320.21 17 3422.23 3826.70 4538.36 4514.32 4473.82 4496.43 3871.45 3541.73 18 3780.62 4024.19 4949.61 5019.96 5046.81 4678.95 4008.34 3592.90 19 3794.63 4177.16 4985.91 5117.22 5155.96 5175.68 4155.76 3719.61 20 4238.23 4382.31 5284.27 5316.25 5369.13 5255.36 4362.74 3915.42 21 4303.29 4486.28 5351.71 5442.84 5477.50 5394.51 4619.28 4114.00 22 4392.98 4722.09 5603.35 5627.06 5815.06 5686.64 4798.55 4274.19 23 4437.62 4860.41 5821.23 5876.20 5993.37 4857.54 4445.07 24 4583.17 5106.52 5988.22 5076.37 4508.07 25 4769.86 5179.68 5158.50 4651.11 26 4863.19 5271.08 5363.99 4808.97 27 5078.04 5452.17 5500.44 4897.84 28 5172.25 5621.11 5606.73 5045.00 29 5380.21 5758.89 5840.10 5320.22 30 5406.48 5568.91

In Table 5, a means that the vibration width is large in the same mode, and the rest means that the vibration width is small in the same mode. Compared to six models before correction, namely A, B, C, D, E, and F, the frequency range of 2000 to 4000Hz, which is mainly a problem in terms of noise, the number of modes in which C and F models have a large vibration width You can see it appearing less. However, the number of modes in the upward direction (Z-axis) of the cover, which is considered to be mainly a problem for noise, is the smallest in E and in the order of C, F and D. From this result, the shape of the cover is most advantageous for the E model, followed by the C or F model.

For the six models, the E model with the positive (+) type beads (D + (+) type beads) on the top of the air layer and disc showed the best results in the finite element analysis. F model with "type bead addition (D + (x) type bead) is advantageous. In other words, the E model is difficult to manufacture in the current HDD manufacturing process. Therefore, the embodiment of the present invention provides a modified HDD cover structure based on the F model. That is, the HDD cover structure modified by the G model and H model shown in Table 5 is provided. In the future, if the E model is easy to manufacture due to the improvement of the HDD manufacturing process, the modified HDD cover structure based on the E model will be implemented.

9 is a diagram of a HDD cover according to a preferred embodiment of the present invention, showing a cover state in which the cover damper is removed (G model).

Referring to FIG. 9, air layers 102, 104, 106, and 108 are formed on the cover 100. The air layers 102, 104, and 106 are formed in subdivisions above the disk so that the cover surface on the disk has a (x) -shaped bead shape. That is, the air layers 102, 104, 106 are formed in the cover surface edge detail about the rotation center axis A1 of the spindle motor 30 shown in FIG. The air layer 108 is formed in a rectangular shape on the side of the VCM. That is, the rectangular air layer 108 is formed in the vicinity of the right side which is one side away from the pivot axis A2 of the actuator 40 by a fixed distance. The vicinity of the right is where the FPC cable is located.

FIG. 10 is a diagram illustrating a HDD cover according to an exemplary embodiment of the present invention, showing a state in which a cover damper 110 is attached to a cover 100 of FIG. 9. The HDD cover shown in FIG. 10 is a G model in which (x) type beads (D + (x) type beads) are added to the air layer and the upper portion of the disk, and a damper is attached. 11 is a cross-sectional view taken along the line B-B 'of the HDD cover of FIG.

Table 6 shows the physical properties and thicknesses of the cover 100 and the cover damper 110 used for the HDD cover shown in FIG. 10 according to an embodiment of the present invention.

property Cover (100) Cover Damper (110) density (㎏ / ㎥) 2646 7860 elastic modulus (Gpa) 70 200 poisson ratio 0.33 0.3 thickness (mm) 0.8 0.8

The physical properties shown in Table 6 were the same as the physical properties shown in Table 3, but the thickness of the cover 100 was changed to 0.8 mm. In Table 3, the thickness of the plate ① was set to 2.6 mm. In addition, referring to Table 6, the cover damper 110 is selected as a material having a higher density than the cover 100. The material of the cover 100 is aluminum, and the material of the cover damper 110 is steel.

Table 7 shows the physical properties of the air between and around the cover 100 and the cover damper 110, as shown in Table 4. In Table 7, the air layers 102, 104, 106, 108 and the outside air between the cover 100 and the cover damper 110 are assumed to have the same physical properties for convenience of analysis.

air gap (mm) density (㎏ / ㎥) soundvelocity (m / s) 2 1.21 340

FIG. 12 shows the physical properties and thicknesses of the cover 100 and the cover damper 110 and the air gaps 102, 104, 106, and 108 of Tables 6 and 7.

In the exemplary embodiment of the present invention, as shown in FIG. 9, the HDD cover without the cover damper 110 is designated as a 'G' model, and the HDD cover with the cover damper 110 is designated as the 'H' model as shown in FIG. 10. Measured.

Noise emitted through the HDD cover while the HDD is operating is mainly affected by the vertical mode of the HDD cover. Therefore, it is reasonable to compare the number of problematic modes rather than comparing the total number of modes in the frequency band of interest (2000 Hz to 4000 Hz).

As a result of analysis, the overall number of modes did not decrease, but the mode corresponding to the cover top was reduced.

FIG. 13 is a view comparing the number of modes in the cover vertical direction (Z-axis) of seven cover models except the free boundary model (Model A). Looking at the number of the cover-up (Z-axis) mode for the seven cover models, namely B, C, D, E and F models and the modified G and H models shown in FIG. The results show improved results in terms of noise and vibration. In particular, since the mode rarely appears for a problem frequency band 2000 to 4000 Hz, it can be seen that the application of the H model is quite advantageous in solving the noise and vibration problems.

In the embodiment of the present invention, the vibration and noise of the HDD model to which the modified HDD cover (model H shown in FIG. 10) was applied were measured by an experimental method.

First, in order to examine the experimental method of vibration of HDD cover, the vibration measurement targets were set to the model with the modified cover and the model with the cover before modification, and each vibration was measured and compared with each other. The measurement was performed by driving the HDD in the idling state in the HDA state (the entire HDD assembled state) to take a vibration value at a predetermined measurement point on the upper surface of the cover. In order to maintain the same condition, the body was not replaced and only the cover was reassembled and the measurement was repeated.

(A), (b) and (c) of FIG. 14 compare vibration vibrations of an idling state with respect to a model before modification, a model modified (G model), and a model (H model) in which the cover damper 110 is added to the modified model. It is shown. The pre-corrected model and the modified model do not show much difference as a whole. However, it can be seen that the large peaks around 3100 Hz were significantly reduced in models (b) and (c) with modified cover. In addition, in case of the model (H model) to which the cover damper 110 is added, the vibration displacement is significantly reduced compared to the first two models.

Next, in order to examine the experimental method of noise of HDD cover, sound pressures of the models with the modified cover and the model with the modified cover and the model with the cover damper were measured and compared. In the measurement, the sound pressure was measured using a microphone at 30 cm above the cover by driving the HDD in the idling state in the HDA state (the entire HDD assembled state). In order to maintain the same condition, the body was not replaced and only the cover was reassembled and the measurement was repeated.

15 shows three types of cover application models, namely, a cover application model before modification (a), a modified cover application model (b), and a modified cover and cover damper application model (c) in an idling state to achieve a 1/3 sound pressure. It is the result measured by an octave band. Referring to the results shown in FIG. 15, the before-correction cover application model (a) and the modified cover application model (b) show no significant difference in the overall sound pressure level. At the overall level, however, the modified model appears to be about 0.3 dB larger. Looking at the frequency bands, the modified cover model shows higher sound pressure than the cover model before correction in the frequency band with the center frequency of 800Hz and the frequency band with 5KHz. However, in the frequency band 2000Hz to 4000Hz, which was a problem when measuring noise, it shows a smaller result. As shown in the vibration result, the model with the cover damper (H model) was found to be significantly reduced compared with the other two models.

In the above description of the present invention, an example of the H model is given as the most preferable model, but the B, C, D, E, and F models may also be applied as embodiments of the present invention, and various modifications and changes may be made to the scope of the present invention. It can be done without departing from. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be defined by the equivalent of claims and claims.

As described above, the present invention minimizes internal noise and vibration of the HDD by manufacturing the HDD cover with a structure having an air layer between the cover and the cover damper.

Claims (13)

In the cover structure of a hard disk drive, Hard disk drive cover structure characterized in that the air layer is formed between the cover and the cover damper attached on the cover. The hard disk drive cover structure of claim 1, wherein the air layer is formed by recessing a predetermined portion of an upper surface of the cover. The hard disk drive cover structure as claimed in claim 2, wherein the air layer is formed on a cover surface above the disk and on one cover surface spaced apart by a predetermined distance from the pivot axis of the actuator. 4. The hard disk drive cover structure of claim 3, wherein a plurality of air layers are formed on the cover surface above the disk. 4. The hard disk drive cover structure according to claim 3, wherein the air layer on the cover surface above the disk is formed in detail on the cover surface about the central axis of rotation of the spindle motor. 5. The hard disk drive cover structure according to claim 4, wherein the cover surface on the disk has an "x" -shaped bead by a plurality of air layers formed on the cover surface on the disk. 5. The hard disk drive cover structure according to claim 4, wherein the cover surface on the disk has a "+"-shaped bead by a plurality of air layers formed on the cover surface on the disk. The hard disk drive cover structure of claim 2, wherein the air layer is formed on one side of the cover surface spaced apart by a predetermined distance from the pivot axis of the actuator. The hard disk drive cover structure according to claim 3, wherein the air layer formed on one side of the cover surface separated by a predetermined distance from the pivot axis of the actuator is formed in a rectangular shape. The hard disk drive cover structure of claim 1, wherein the air layer is several millimeters (mm). In the hard disk drive cover structure, In order to reduce vibration and noise on the hard disk drive cover, the cover is attached to the stepped cover surface portion and the cover by putting a step on the upper portion of the disk on the cover surface and one cover surface portion separated by a certain distance from the pivot axis of the actuator. A hard disk drive cover structure characterized in that an air layer is formed between dampers. The hard disk drive cover structure of claim 11, wherein the cover and the cover damper have a thickness of 0.8 mm and the air layer has a thickness of 1 to 2 mm. 13. The hard disk drive cover structure of claim 12, wherein the cover damper is a material having a higher density than the cover.